This invention relates to seals for preventing the escape of gas around a valve door in a diverter valve used to divert gas flow in a duct.
In ducts used to direct the flow of gases, such as turbulent, high temperature waste gas from a gas turbine, a diverter valve having a body with at least three openings for connection to gas conduits includes a door which pivots to alternately block flow through one of two of the openings. A typical diverter valve can include one opening used as an inlet for hot gases, two openings used as outlets, and a door pivotable between a first position closing one of the outlets and a second position closing the other outlet. In such an arrangement, it is important to provide seals between the valve body and the door to prevent the leakage of the gas through the closed outlet. In prior art diverter valves, seals have been provided in the form of leaf seal members which allow an unacceptable amount of leakage. In order to prevent the escape of gas around the door of a diverter valve, a plurality of leaf seal members must together define a closed figure such as a rectangle. However, the leaf seal members forming the individual sides of the rectangle cannot be joined to one another since they will move closer to one another or farther from one another at their juncture as they are deflected by the door. The inability of the leaf members to be joined means that overlaps or gaps at the junctures are present, which results in leakage past the seal at the junctures.